in my opinion, why some country in asia was banned to use bitcoin : because bitcoin is electronic data. Thus, it’s not considered a currency and can’t be used for payments, and is not considered legal tender like money. With no self worth, the value of such data varies based on the needs of the market. Bitcoin changes in value very quickly and it could became something of no value if none desired it.
Effectively, bitcoin is just electronic data with no intrinsic value, and its value rises or falls depending upon the whims of the market. Furthermore, consumers' legal recourse will be severely limited in the case of any claims over coins stolen or sent to the wrong wallet, or over goods purchased with bitcoin but not received.
for example bitcoin illegal  some asia country is thailand, Over the past nine months, the illegal status of cryptocurrencies in Thailand has been an issue of great confusion but bank of Thailand just Suggests Bitcoin Not Illegal But Warns Against its Use.